Oil Hydrocarbons Research Articles

Co-hydropyrolysis of pine and HDPE over bimetallic catalysts: Efficient BTEX production and process mechanism analysis

Co-pyrolysis of plastics and biomass is expected to replace traditional petroleum processing to produce BTEX (benzene, toluene, ethylbenzene, and xylenes) on a large scale, which are important chemical raw materials. The introduction of bimetallic catalysts and hydrogen in co-pyrolysis systems is an effective strategy to increase the content of aromatic hydrocarbons in pyrolysis oils, which has not been studied so far. The present study investigated the efficacy of bimetallic catalysts in enhancing aromatization and Diels-Alder reactions in comparison to Mo/ZSM-5. The synergistic interaction between bimetals contributed to the improved selectivity of aromatic hydrocarbons, particularly BTEX. Results revealed that NiMo/ZSM-5 catalysts led to higher aromatics selectivity in liquid oil, whereas FeMo/ZSM-5 resulted in higher BTEX selectivity in aromatic hydrocarbons. Moreover, metal oxide-supported bimetallic catalysts exhibited lower selectivity for aromatic hydrocarbons in liquid oil, despite facilitating higher liquid-oil yield. Among the metal oxide-supported bimetallic catalysts, FeMo/TiO2 demonstrated the highest selectivity (56%) for aromatic hydrocarbons in liquid oils. The introduction of hydrogen resulted in 100% selectivity of BTEX in aromatic hydrocarbons, thus highlighting the significance of hydrogenation in enhancing the selectivity of BTEX. Combined with the experimental results and literature, a possible reaction mechanism was also proposed.

Enrichment factors of movable hydrocarbons in lacustrine shale oil and exploration potential of shale oil in Gulong Sag, Songliao Basin, NE China

The geological characteristics and production practices of the major middle- and high-maturity shale oil exploration areas in China are analyzed. Combined with laboratory results, it is clear that three essential conditions, i.e. economic initial production, commercial cumulative oil production of single well, and large-scale recoverable reserves confirmed by the testing production, determine whether the continental shale oil can be put into large-scale commercial development. The quantity and quality of movable hydrocarbons are confirmed to be crucial to economic development of shale oil, and focuses in evaluation of shale oil enrichment area/interval. The evaluation indexes of movable hydrocarbon enrichment include: (1) the material basis for forming retained hydrocarbon, including TOC>2% (preferentially 3%–4%), and type I–II1 kerogens; (2) the mobility of retained hydrocarbon, which is closely related to the hydrocarbon composition and flow behaviors of light/heavy components, and can be evaluated from the perspectives of thermal maturity (Ro), gas-oil ratio (GOR), crude oil density, quality of hydrocarbon components, preservation conditions; and (3) the reservoir characteristics associated with the engineering reconstruction, including the main pore throat distribution zone, reservoir physical properties (including fractures), lamellation feature and diagenetic stage, etc. Accordingly, 13 evaluation indexes in three categories and their reference values are established. The evaluation indicates that the light shale oil zones in the Gulong Sag of Songliao Basin have the most favorable enrichment conditions of movable hydrocarbons, followed by light oil and black oil zones, containing 20.8×108 t light oil resources in reservoirs with Ro>1.2%, pressure coefficient greater than 1.4, effective porosity greater than 6%, crude oil density less than 0.82 g/cm3, and GOR>100 m3/m3. The shale oil in the Gulong Sag can be explored and developed separately by the categories (resource sweet spot, engineering sweet spot, and tight oil sweet spot) depending on shale oil flowability. The Gulong Sag is the most promising area to achieve large-scale breakthrough and production of continental shale oil in China.

Biochars Affect the Mobility of Carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs) in Amended Soil and Their Bioaccumulation in Spinach

Biochars Affect the Mobility of Carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs) in Amended Soil and Their Bioaccumulation in Spinach

FEATURES OF THE DISTRIBUTION AND COMPOSITION OF ORGANIC COMPOUNDS IN WATER AND BOTTOM SEDIMENTS CHERNAVKA RIVER FLOWING INTO ELTON LAKE

Organic compounds: Corg, lipids, hydrocarbons (HCs) – aliphatic (AHCs) and polycyclic aromatic (PAHs) in suspended particulate matter of surface waters and in bottom sediments of the shallow Chernavka River, which flows into a self-sustaining Elton Lake were studied. High concentrations of organic compounds were found in surface waters: in averaged 692, 80 and 0.79 µg/L for lipids, AHCs, and PAHs respectively. The composition of alkanes in the aqueous suspension corresponded to the weathered oil hydrocarbons. HC transformation occurs here not in the course of sedimentation, but at the water–bottom sediment interface. As a result, the AHC composition of the sediments differed from that of the particulate matter in the presence of planktonogenic low molecular weight homologues of n C15–C17 and a sharp increase in the series of odd high molecular weight alkanes, while the PAH composition differed in the increase in the proportion of naphthalene.

Occurrence, seasonal variations, distribution patterns, and risk assessment of volatile monoaromatic hydrocarbons in soils of industrial parks in Yangtze River Delta, China

Monoaromatic hydrocarbons (MACHs) are a ubiquitous category of volatile compounds found in various environmental media. Despite their prevalence, systematic studies of MACHs on a large regional scale are still lacking. Herein, a comprehensive investigation of the occurrence, seasonal variations, distribution characteristics, and health risks of MACHs was carried out by analyzing soil samples (372 surface soils and 96 soil columns) from 33 typical industrial parks in the Yangtze River Delta (YRD) region. MACHs were detected in all surface soil samples. BTEXS (benzene, toluene, ethylbenzene, xylene, and styrene) were the five predominant congeners with the highest detection frequencies (90.9 %–100 %), collectively accounting for >78.2 % of the total MACHs content. Higher residual levels of MACHs were observed in winter compared to summer (P < 0.01), with total concentrations of 24 MACHs ranging from 30.9 ng/g to 1536 ng/g (median: 135 ng/g) in winter and 16.3 ng/g to 931 ng/g (median: 87.9 ng/g) in summer. Soils collected from the northeast of Jiangsu Province and the southwest of Anhui Province exhibited relatively higher levels of MACHs. On the basis of principal component analysis, we proposed that industrial emissions and vehicle exhaust may be the main sources of MACHs contamination in the soils of YRD industrial parks. Vertically, the concentrations of total MACHs decreased with the soil depth. Soil organic matter (OM) content and the concentration of MACHs in the surface soil layer (0–15 cm) were significant factors influencing the vertical migration and distribution of MACHs (P < 0.05). It was verified that residual MACHs in the soils posed lower lifetime non-carcinogenic and carcinogenic risks to the inhabitants of the study area. The field study provides valuable evidence for the formulation of MACHs pollution control policies in the YRD region.

THE CHOICE OF INDICATORS FOR THE ECOLOGICAL RATIONING OF PETROLEUM PRODUCTS IN CHESTNUT SOILS

The response of the microbial community of soils to dif erent levels of oil contamination in a model experiment was studied according to indicators: basal respiration (BR), basal induced respiration (SIR), carbon of microbial biomass (Cmic), potential denitrif cation (DNF), methanogenesis, catalase activity. The soils are represented by light chestnut (Haplic Kastanozems Sodic) and meadow-chestnut (Gleyic Kastanozems Chromic) drysteppe zone of the Stavropol area, dif ering in the organic matter content, salinity and the content of physical clay. The intensity of BR increased af er 30 days of the crude oil input into the soils and caused the growth of Cmic due to the activation of oil-oxidizing microorganisms in anaerobic zones of soils. DNF varied in light chestnut and meadow-chestnut soils not directly, that was probably due to the level of organic matter content in soils and their salinity. Catalase activity was a sensitive indicator for the petroleum hydrocarbons in light chestnut soil, but salinity was the determining factor in its activity in meadow chestnut soil. Biotesting with the use of worms Eisenia fetidashowed the inability of test organisms to survive in non-contaminated chestnut soils. A significant indicator that did not depend on natural factors in chestnut soils was BR and related indicators. Catalase activity and DNF have limitations on the salinity factor.

Concentrations, Source Identification and Potential Ecological and Human Health Risks Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Agricultural Soils of Hamedan County, West of Iran

ABSTRACT This study was performed to examine the possible ecological impact of sixteen PAHs listed as priorities by the US EPA in the agricultural soils of Hamedan County (ASHC), west of Iran, in 2021. In so doing, 36 surface soil samples were collected from 12 agriculturally-related sampling locations. The soxhlet method was employed to extract analytes, and the gas chromatography/mass spectrometry (GC-MS) method was utilized to identify the chemicals PAHs in the samples. Based on the data, there were 16PAHs (∑16PAHs) in total concentrations (µg kg−1), ranging from 435 to 3292, with an average of 1806. The PAH profiles were dominated by PAHs with larger molecular weights (≥4 rings), accounting for 78% of the total mass of 16PAH. Based to Molecular Diagnostic Ratios (MDRs) the majority of PAH molecules were found to have pyrogenic origins. As the results indicated, Indeno(1,2,3-cd)pyrene and benz(ghi)perylene posed very little ecological harm to soil organisms, based on the data, while other PAHs reflected significant environmental risks in these soils. All of the stations were identified as being in the low-risk group by the overall ecological risk of 16PAH in surface soil samples. The total incremental lifetime cancer risks (Total ILCRs) of PAH compounds for children with an average of 7.51 × 10−7 (ranging from 1.66 × 10−7 to 1.50 × 10−6) indicated negligible potential cancer and human health risks; whereas, the total ILCRs for adults with an average of 1.59 × 10−6 (ranging from 3.65 × 10−7 to 3.30 × 10−6) showing a low potential carcinogenic risk of PAH compounds in the study location. These findings imply that eating food cultivated in contaminated soils and directly digesting soil may be harmful to human health. Therefore, regular and periodic monitoring of agricultural soils is recommended to maintain consumer’s health of agricultural products.

Geochemical evidence for Alberta Oil Sands contamination in sediments remote to known oil sands deposits in Alberta, Canada

Oil spills and natural oil seeps are sources of petrogenic hydrocarbons in soils and sediments. To determine the source of hydrocarbon contamination in the environment the geochemical signature of the contaminant needs to be characterised. Here, we present biomarker and other molecular marker diagnostic ratios of Alberta Oil Sands using gas chromatography-mass spectrometry to characterise the deposits and detect their incorporation in surficial sediments. Diagnostic ratios of steranes, terpanes, and aromatic steroids (e.g. C27, C28, and C29 regular sterane abundance, Gammacerane Index, Ts/Tm, TAS/(TAS + MAS), and MPI-2) were measured in samples of Alberta Oil Sands providing a set of criteria for their identification. Seven surficial sediment samples from central and southeast Alberta were then analysed using these criteria to detect Alberta Oil Sands contamination and other petrogenic and pyrogenic source inputs. Geochemical signatures consistent with Alberta Oil Sands hydrocarbons were identified in surficial sediments in Lamont County and glacial sediments from a moraine in Beaver County. Both sites are in Central Alberta, ∼300 km south of any oil sands extraction sites and natural exposures in northern Alberta, indicating long-distance sediment transport processes mobilised the deposits. These results show that the oil sands have been eroded and transported beyond the boundaries of their current known limits. This is important for understanding sediment transport processes as well as for remediation and reclamation purposes.

New insight into the effect of nitrogen on hydrocarbon degradation in petroleum-contaminated soil revealed through 15N tracing and flow cytometry

Nitrogen (N) has been widely used to dissipate total petroleum hydrocarbons (TPH) in the oil-contaminated soil, but the relationships of hydrocarbon transformation, N cycling and utilization, and microbial characteristics during TPH biodegradation still remain unclear. In this study, 15N tracers (K15NO3 and 15NH4Cl) were used as stimulants for TPH degradation to compare the bioremediation potential of TPH in the historically (5 a) and freshly (7 d) petroleum-contaminated soils. During bioremediation process, TPH removal and carbon balance, N transformation and utilization, as well as microbial morphologies were investigated using 15N tracing and flow cytometry. Results showed that TPH removal rates were higher in the freshly polluted soils (61.59 % for K15NO3 amendment and 48.55 % for 15NH4Cl amendment) than in the historically polluted soils (35.84 % for K15NO3 amendment and 32.30 % for 15NH4Cl amendment), and TPH removal rate through K15NO3 amendment was higher than that of 15NH4Cl in the freshly polluted soils. This result was attributed to the higher N gross transformation rates in the freshly contaminated soils (0.0034–0.432 mmol N kg−1 d−1) when compared with that in the historically contaminated soils (0.009–0.04 mmol N kg−1 d−1), which led to more TPH transformation to residual carbon (51.84 %–53.74 %) in the freshly polluted soils than that in the historically polluted soils (24.67 %–33.47 %). Based on the fluorescence intensity displayed by the combination of stains and cellular components to indicate microbial morphology and activity, flow cytometry analysis showed that nitrogen addition was beneficial for the membrane integrity of TPH-degrading bacteria, and nitrogen also enhanced DNA synthesis and activity of TPH-degrading fungi in freshly polluted soil. Correlation and structural equation modeling analysis identified that K15NO3 was beneficial to synthesize DNA of the TPH-degrading fungi but not the bacteria, which contributed to enhance TPH bio-mineralization in the soils with K15NO3 amendment.

Exfoliated graphite with γ-Fe2O3 for the removal of oil and organic pollutants from the water surface: Synthesis, Mossbauer study, sorption and magnetic properties

Exfoliated graphite (EG) is a promising sorbent for oil and organic pollutants, which has a high sorption capacity and hydrophobicity. Modifying the EG with ferrimagnetic compound allows EG with sorbed oil to be collected from the water surface with the use of a magnetic field. The aim of this work is to obtain a sorbent based on exfoliated graphite with ferrimagnetic maghemite (γ-Fe2O3) and investigate its structure and functional properties. The preparation of iron-containing EG includes the impregnation of expandable graphite with a FeCl3 water solution and the thermal treatment of impregnated expandable graphite at temperatures between 400 and 1000 °C. Mossbauer spectroscopy, X-ray diffraction analysis, scanning electron microscopy and energy dispersive X-ray spectroscopy show the evolution of the iron-containing phase from FeOCl to the mixture of α-Fe2O3 and γ-Fe2O3, which grants magnetic properties to the samples. EG obtained at 1000 °C has a saturation magnetization of 22.7 emu g−1. High macropore and meso-/micropore volume investigated by mercury porosimetry and nitrogen adsorption-desorption method results in a high sorption rate and sorption capacity of EG up to 30 g g−1 toward oil and liquid hydrocarbons. At the same time, the EG sorption capacity toward water is ten times lower.

Theoretical and methodological approaches to identifying deep accumulations of oil and gas in oil and gas basins of the Russian Federation

A large number of oil and gas accumulations at deep and ultra-deep depths, recently revealed in the world due to the development of drilling technologies, forces a revision of theoretical ideas on many issues, including conditions of oil and gas formation and hydrocarbon conservation in zones of high pressures and temperatures, as well as evaluating the possibility of conservation and formation of reservoirs. Among the most discussed, in this regard, are the issues determining the processes and rate of oil and gas formation at deep and ultra-deep depths, which differ significantly from those at small and medium depths: Thermobaric conditions responsible for the possibility of formation, phase distribution and conservation of hydrocarbons, geochemical indicators—type of kerogen, and its transformation, responsible for the phase distribution and staging of generation peaks—lithological composition of kerogen-bearing strata—the rate and scale of dip and uplift and the timing of exposure to high temperatures—the formation of overlapping saline strata and the presence of deep conductive faults that significantly affect temperature and pressure gradients. Analysis of the influence of the above factors on the prospects of deep-lying complexes taking into account new studies and achievements, mainly in the sedimentary basins of China (Tarim, Jungar, Ordos, Sichuan), the Gulf of Mexico and offshore Brazil (Santos) allowed typifying the sedimentary basins and major depressions of Russia, with the allocation of areas with high and ultra-low depth potential for hydrocarbon studies. Thermobaric and historical and geological criteria have been developed and a methodology for detailed study of promising areas has been proposed, including a complex of geochemical studies of hydrocarbons, extracts of bitumoids (pyrolytic, chromatographic) and lithological and petrophysical core studies aimed at assessing the prospects of oil and gas content of deep complexes in Russian sedimentary basins and the subsequent localization of the most promising areas for deep drilling.

MODELING AND FEATURES OF OIL POLLUTION IN THE LENS (ISLAND) PERMAFROST

The article discusses the processes of soil pollution by oil hydrocarbons in conditions of lens and permafrost. The authors use the methods of mathematical modeling, methods of experimental observations, comparative analysis. The risks of leaks and spills of oil hydrocarbons are indicated as an extremely important issue requiring study using various methods. Brief reviews of the results of studies of soil pollution by oil hydrocarbons are given. A brief analysis of the dynamics of soil pollution by oil hydrocarbons is presented. A hypothesis has been put forward that, when stability is disturbed in lens permafrost, the dynamics of pollutant distribution differs significantly from the dynamics of their distribution under normal conditions. Photographs, drawings, schemes of the distribution of pollutants within the lens and permafrost formations are given. The results of the initial modeling of the spreading of oil hydrocarbons within permafrost lens formations are presented. The process of modeling soil pollution with oil products in conditions of lens permafrost is divided into two stages: the primary modeling of pollution of the permafrost lens itself and the model of the secondary process, when pollutants bypass lens permafrost in the process of diffusion and enter non-frozen soil. The model involves the calculation of areas – pollution halos, as well as the calculation of the surface concentration of pollutants in them. It is concluded that the composition of oil sludge formed with the participation of pollutants is determined by many factors – climatic, physical and chemical, characteristics and composition of the soil. It is concluded that, due to climatic conditions and the state of island (lens) permafrost, the pollution process can differ significantly in dynamics.

π-hole bonding: A new retention mechanism for the solid phase extraction of polycyclic aromatic hydrocarbons from the hexane extracts of soil samples.

In this work, the perfluorobenzene-bonded silica sorbent was tested to adsorb polycyclic aromatic hydrocarbons in hexane. In the comparison experiments, perfluorobenzene-bonded sorbent's performance was better than octadecyl silica sorbent and phenyl bonded silica sorbents, which indicated that the π-hole···π bonds between perfluorobenzene and the polycyclic aromatic hydrocarbons were stronger than π···π interactions and hydrophobic interactions in hexane. Then the perfluorobenzene-bonded silica sorbent was applied to solid phase extraction of 15 polycyclic aromatic hydrocarbons from the hexane extracts of soil samples directly without the solvent replacement, which simplified the soil pretreatment process. And the results showed that under the optimal conditions, the proposed method for the determination of polycyclic aromatic hydrocarbons in the environment soil presented good recoveries and stabilities for the 10 heavier polycyclic aromatic hydrocarbons with the recoveries ranging from 75.1% to 104.6% and the relative standard deviations being in the range of 1.4%-5.8%. The limits of detection of the method varied from 0.1 to 2 ng·g-1 . This work reveals the great application potential of π-hole bond as a new retention mechanism in the field of solid phase extraction. This article is protected by copyright. All rights reserved.

Pollution Characteristics and Risk Assessment of PAHs in the Soil of Wild Forsythia Suspensa in Shanxi

Shanxi is one of the main producing areas of Forsythia suspensa in China. In order to explore the safety of the soil in the areas where Forsythia suspensa grows,70 surface (0-25 cm) soil samples were collected from the main growing areas of F. suspensa in the eastsouth of Shanxi Province in July 2017. The concentration and composition characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in the sample soils were analyzed using chemical extraction and gas chromatography-mass spectrometry (GC-MS). The diagnostic ratio method was used to determine the source of PAHs in the areas. The potential ecological risk was assessed by using the method of calculating the equivalent carcinogenic concentration of benzo[a]pyrene. The results showed that the average concentration of total PAHs (Σ16PAHs) in all of the soil samples was 1.85 μg·g-1, which was dominated by three ring number PAHs, accounting for 76.7% of the total PAHs. The detection rates of phenanthrene (Phe) and anthracene (Ant) were both 100% of all the sample sites. The soil PAHs in the wild F. suspensa growing areas mainly originated from coal, biomass burning, and motor vehicle exhaust emissions, which resulted from air transport and sedimentation pathways. In all of the sample sites, the concentration of Σ16PAHs the limit standard level (0.2 μg·g-1) of Maliszewska-Kordybach for agricultural soil pollution and exceeded the soil heavy pollution level limit value (1.0 μg·g-1) in 41.4% of the sample sites. The concentration of BaP was above the risk control standard for soil contamination of agricultural land (0.55 μg·g-1) in 10% of all the soil samples. A total of 11.4% of the sample soil ΣBaPeq16PAHs and ΣBaPeq8BPAHs exceeded the agricultural soil screening value (0.55 μg·g-1). These results indicate that the contamination of PAHs was at a detectable level in the soil of wild F. suspensa growing in Shanxi, and thus their potential ecological risks should not be ignored. It is necessary to enhance the research regarding these areas to ensure the safe production of medicinal plants.

Developing a parametric system model to describe the product distribution of steam pyrolysis in a Dual Fluidized bed

Steam pyrolysis is a thermochemical process that converts carbon-based materials into valuable gases. In general, the products of the reaction are syngas (H2,CO,CO2), low-molecular-weight hydrocarbon gases (methane, ethylene, and propylene), pyrolytic gasoline and oils, monoaromatic and polyaromatic species (tar), and carbonaceous residues (char) with ashes. However, the intricacy of the reactions comprising the process, the diversity of the product species, and the constraints linked to the sampling and measurement equipment, create a highly complex system. In this work, a method for data representation is presented based on a special Parametric System Model (PSM) that portrays product species measurements in a way that provides relevant information and valuable insights into the process. The method incorporates generic knowledge of the chemical nature of the reactions to create a constrained system in which the data can be expressed in parametric terms with meaningful statistical functions. The evaluated data were obtained from a high-temperature steam pyrolysis process performed in the 2–4-MW Dual Fluidized Bed reactor at Chalmers University using polyethylene as feedstock. The quantities of the hydrocarbon species detected in the gas product were taken for the PSM as a probabilistic system that can be described with a set of distribution functions. The carbon, hydrogen and oxygen balances were taken into account to build a constrained set of equations to find the parameters of the functions. The resulting model was proven to be useful as a prediction tool to quantify unmeasured carbon group species and to estimate process variables, such as the oxygen transport of the bed material. Also, it was demonstrated the potential of the model as a method to identify and estimate inconsistencies in the measurements, which improve the quality of the characterization data. The modeĺs outcomes find application in providing critical information for the control and evaluation of pyrolysis process and downstream operation of biorefineries.

The role of comprehensive two-dimensional gas chromatography in mineral oil determination.

Mineral oil hydrocarbons (MOH) contain a wide structural diversity of molecules, for which the reference method of analysis is the online coupled liquid chromatography-gas chromatography with flame ionization detection (LC-GC-FID). These compounds are very heterogeneous from a toxicological viewpoint, and an accurate risk assessment when dealing with a MOH contamination can only be performed if sufficient information is available on the types of structures present (i.e., number of carbons, degree of alkylation, number of aromatic rings). Unfortunately, the separation performances of the current LC-GC-FID method are insufficient for such characterization, not even mentioning the possible coelution of interfering compounds which additionally hinder MOH determination. Comprehensive two-dimensional gas chromatography (GC × GC), while mostly used for confirmation purposes in the past, starts to prove its relevance for overcoming the weaknesses of the LC-GC method and reaching even better the analytical requirements defined in the latest EFSA opinion. The present paper therefore aims at highlighting how GC × GC has contributed to the understanding of the MOH topic, how it has developed to meet the requirements of MOH determination, and how it could play a role in the field for overcoming many of the current analytical and toxicological challenges related to the topic.

Efficiency and mechanism on photocatalytic degradation of fluoranthene in soil by Z-scheme g-C3N4/α-Fe2O3 photocatalyst under simulated sunlight.

Polycyclic aromatic hydrocarbons (PAHs) in soil have potential harm on human health. However, remediation of PAH-contaminated soils through photocatalytic technology remains a challenge. Therefore, the photocatalyst g-C3N4/α-Fe2O3 was synthesized and applied to photocatalytic degradation of fluoranthene in soil. The physicochemical properties of g-C3N4/α-Fe2O3 and various degradation parameters, such as catalyst dosage, the ratio of water/soil, and initial pH, were investigated in detail. In soil slurry reaction system (water/soil=10:1, w/w), the optimal degradation efficiency on fluoranthene was 88.7% after simulated sunlight irradiation for 12 h (contaminated soil=2 g, initial fluoranthene concentration=36 mg/kg, catalyst dosage=5%, and pH=6.8), and the photocatalytic degradation followed pseudo-first-order kinetics. The degradation efficiency of g-C3N4/α-Fe2O3 was higher compared with P25. Degradation mechanism analysis showed that •O2- and h+ are the main active species in photocatalytic degradation process of fluoranthene by g-C3N4/α-Fe2O3. Coupling g-C3N4 and α-Fe2O3 enhances the interfacial charge transport capacity via Z-scheme charge transfer route and inhibits the recombination of photogenerated electrons and holes of g-C3N4 and α-Fe2O3, then significantly improves the production of active species and photocatalytic activity. Results showed that photocatalytic treatment of soil by g-C3N4/α-Fe2O3 is an effective strategy for remediation of soils contaminated by PAHs.

Introducing a land use-based weight factor in regional health risk assessment of PAHs in soils of an urban agglomeration

The high heterogeneity of land uses in urban areas has led to large spatial variations in the contents and health risks of polycyclic aromatic hydrocarbons (PAHs) in soils. A land use-based health risk assessment (LUHR) model was proposed for soil pollution on a regional scale by introducing a land use-based weight factor, which considered the differences in exposure levels of soil pollutants to receptor populations between land uses. The model was applied to assess the health risk posed by soil PAHs in the rapidly industrializing urban agglomeration of Changsha-Zhuzhou-Xiangtan Urban Agglomeration (CZTUA). The mean concentration of total PAHs (∑PAHs) in CZTUA was 493.2 μg/kg, and their spatial distribution was consistent with emissions from industry and vehicles. The LUHR model suggested the 90th percentile health risk value was 4.63 × 10−7, which was 4.13 and 1.08 times higher than those of traditional risk assessments that have adopted adults and children as default risk receptors, respectively. The risk maps of LUHRs showed that the ratios of the area exceeding the risk threshold (1 × 10‐6) to the total area were 34.0 %, 5.0 %, 3.8 %, 2.1 %, and 0.2 % in the industrial area, urban green space, roadside, farmland, and forestland, respectively. The LUHR model back-calculated the soil critical values (SCVs) for ∑PAHs under different land uses, resulting in values of 6719, 4566, 3224, and 2750 μg/kg for forestland, farmland, urban green space, and roadside, respectively. Compared with the traditional health risk assessment models, this LUHR model identified high-risk areas and drew risk contours more accurately and precisely by considering both the spatial variances of soil pollution and their exposure levels to different risk receptors. This provides an advanced approach to assessing the health risks of soil pollution on a regional scale.

Tracking the early signals of crude oil in seawater and plankton after a major oil spill in the Red Sea

Understanding the immediate impacts of oil spills is essential to recognizing their long-term consequences on the marine environment. In this study, we traced the early (within one week) signals of crude oil in seawater and plankton after a major oil spill in October 2019 in the Red Sea. At the time of sampling, the plume had moved eastward, but we detected significant signs of incorporation of oil carbon into the dissolved organic carbon pool, resulting in a 10–20% increase in the ultraviolet (UV) absorption coefficient (a254) of chromophoric dissolved organic matter (CDOM), elevated oil fluorescence emissions, and depletion of the carbon isotope composition (δ13C) of the seawater. The abundance of the picophytoplankton Synechococcus was not affected, but the proportion of low nucleic acid (LNA) bacteria was significantly higher. Moreover, specific bacterial genera (Alcanivorax, Salinisphaera, and Oleibacter) were enriched in the seawater microbiome. Metagenome-assembled genomes (MAGs) suggested that such bacteria presented pathways for growing on oil hydrocarbons. Traces of polycyclic aromatic hydrocarbons (PAHs) were also detected in zooplankton tissues, revealing the rapid entry of oil pollutants into the pelagic food web. Our study emphasizes the early signs of short-lived spills as an important aspect of the prediction of long-term impacts of marine oil spills.

Hetero- and Homogeneous States of Hydrocarbon Fluids in the Earth’s Interior: Evidence from the Study of Synthetic Fluid Inclusions

Based on experiments including in situ studies of the phase composition and states of aqueous–hydrocarbon fluids in synthetic inclusions in quartz, the thermometric data indicating a heterogeneous state of fluids at shallow, medium, and great depths of oil- and gas-bearing layers were obtained. It was shown that aqueous–hydrocarbon fluids with an oil content of ≥10 vol % remain heterogeneous even at depths of up to 10–12 km at temperatures of 250–290°С. As is evident from experiments, homogenization in such fluids was achieved at temperatures above 380–400°C. However, such temperatures have not yet been recorded in any of the real oil and gas basins of the world. The results of our studies allow us to hope for the discovery of homogeneous deep deposits of oil and other hydrocarbons in the future.